243 



Yiilvo it is impossible to determine the genus accurately; l)ut the 

 specimens resemble closely the dorsal valves of a Cyrtina, though 

 the fold is different from that of any described species. In this 

 latter feature the species resembles Cyrtina? amblyr/ona, Phil. 

 Subcarb. Eng. (Davidson, Pal. Soc), and I have therefore referred 

 it provisionally to the same genus. It seems very strange that Avhile 

 dorsal valves of C? Cunq^ira have been found, not a single ventral 

 valve has yet been detected. 



Prof. Hall, who examined the specimens, thought that they might 

 prove to be something besides Cyrtina, but was in doubt as to their 

 generic affinities. They have much the appearance of a Spirifera, 

 but one specimen seems to be marked, though very indistinctly, 

 with line, radiating, raised lines, a character which is unknown in 

 any Spirifera, plicated as this one is. (Morgan Expeditions 1870 

 and '71.) ^ 



It receives its name from Kurupira, Lingoa Geral, a forest spirit 

 of Tupi mythology. 



Retzia* Jamesiaua; Hartt, sp. nov., Plate X, figs. 33 and 27-38. 



Test small, longitudinally suboval in outline, more or less angular poste- 

 riorly, with the greatest width near the middle. Proportions of length to 

 breadth variable ; breadth usually nearly equal to, sometimes three-fourths the 

 length. Ventricose, occasionally flattened and lenticular ; ventral valve more 

 convex than the dorsal. Beak of ventral valve extended beyond the dorsal 

 valve. Valves plicated. 



Ventral valve quite regularly convex, the greatest elevation being at or just 

 behind the middle. The curvature from the front along the median line is usu- 

 ally very regular and moderately strong up to the beak, along which it is slightly 

 more abrupt. From side to side the valve is very strongly convex, and, rising 

 rapidly from the lateral margins, generally with slight curvature, it is regu- 

 larly and well rounded on the median line. Beak projecting considerably beyond 

 the dorsal valve, and rather strongly arcuate. The posterior lateral margins of 

 valve diverge at an angle, varying from a little more to a little less than a 

 right angle ; they may be slightly convex or nearly straight, but are gen- 

 erally somewhat concave for a short distance, when they bend round and join 

 the lateral margins, which, together with the front, form a regular curve equal 

 to a little more than a semicircle. Surface marked by 14-20 low, rounded, 



* Mr. R. P. Whitfield writes me that " the genus Rhijnchospira will have to be dropped en- 

 tirely, as Retzia Adiieni, Vern., appears to be generically the same as R.fortnosa, Hall's typa 

 of Rhynchospira." 



